Text-to-speech REST API

The Speech service allows you to convert text into synthesized speech and get a list of supported voices for a region by using a REST API. In this article, you'll learn about authorization options, query options, how to structure a request, and how to interpret a response.

The text-to-speech REST API supports neural text-to-speech voices, which support specific languages and dialects that are identified by locale. Each available endpoint is associated with a region. A subscription key for the endpoint or region that you plan to use is required. Here are links to more information:

Important

Costs vary for prebuilt neural voices (called Neural on the pricing page) and custom neural voices (called Custom Neural on the pricing page). For more information, see Speech service pricing.

Before you use the text-to-speech REST API, understand that you need to complete a token exchange as part of authentication to access the service.

Authentication

Each request requires an authorization header. This table illustrates which headers are supported for each feature:

Supported authorization header Speech-to-text Text-to-speech
Ocp-Apim-Subscription-Key Yes Yes
Authorization: Bearer Yes Yes

When you're using the Ocp-Apim-Subscription-Key header, you're only required to provide your subscription key. For example:

'Ocp-Apim-Subscription-Key': 'YOUR_SUBSCRIPTION_KEY'

When you're using the Authorization: Bearer header, you're required to make a request to the issueToken endpoint. In this request, you exchange your subscription key for an access token that's valid for 10 minutes.

How to get an access token

To get an access token, you need to make a request to the issueToken endpoint by using Ocp-Apim-Subscription-Key and your subscription key.

The issueToken endpoint has this format:

https://<REGION_IDENTIFIER>.api.cognitive.microsoft.com/sts/v1.0/issueToken

Replace <REGION_IDENTIFIER> with the identifier that matches the region of your subscription.

Use the following samples to create your access token request.

HTTP sample

This example is a simple HTTP request to get a token. Replace YOUR_SUBSCRIPTION_KEY with your subscription key for the Speech service. If your subscription isn't in the West US region, replace the Host header with your region's host name.

POST /sts/v1.0/issueToken HTTP/1.1
Ocp-Apim-Subscription-Key: YOUR_SUBSCRIPTION_KEY
Host: westus.api.cognitive.microsoft.com
Content-type: application/x-www-form-urlencoded
Content-Length: 0

The body of the response contains the access token in JSON Web Token (JWT) format.

PowerShell sample

This example is a simple PowerShell script to get an access token. Replace YOUR_SUBSCRIPTION_KEY with your subscription key for the Speech service. Make sure to use the correct endpoint for the region that matches your subscription. This example is currently set to West US.

$FetchTokenHeader = @{
  'Content-type'='application/x-www-form-urlencoded';
  'Content-Length'= '0';
  'Ocp-Apim-Subscription-Key' = 'YOUR_SUBSCRIPTION_KEY'
}

$OAuthToken = Invoke-RestMethod -Method POST -Uri https://westus.api.cognitive.microsoft.com/sts/v1.0/issueToken
 -Headers $FetchTokenHeader

# show the token received
$OAuthToken

cURL sample

cURL is a command-line tool available in Linux (and in the Windows Subsystem for Linux). This cURL command illustrates how to get an access token. Replace YOUR_SUBSCRIPTION_KEY with your subscription key for the Speech service. Make sure to use the correct endpoint for the region that matches your subscription. This example is currently set to West US.

curl -v -X POST \
 "https://westus.api.cognitive.microsoft.com/sts/v1.0/issueToken" \
 -H "Content-type: application/x-www-form-urlencoded" \
 -H "Content-Length: 0" \
 -H "Ocp-Apim-Subscription-Key: YOUR_SUBSCRIPTION_KEY"

C# sample

This C# class illustrates how to get an access token. Pass your subscription key for the Speech service when you instantiate the class. If your subscription isn't in the West US region, change the value of FetchTokenUri to match the region for your subscription.

public class Authentication
{
    public static readonly string FetchTokenUri =
        "https://westus.api.cognitive.microsoft.com/sts/v1.0/issueToken";
    private string subscriptionKey;
    private string token;

    public Authentication(string subscriptionKey)
    {
        this.subscriptionKey = subscriptionKey;
        this.token = FetchTokenAsync(FetchTokenUri, subscriptionKey).Result;
    }

    public string GetAccessToken()
    {
        return this.token;
    }

    private async Task<string> FetchTokenAsync(string fetchUri, string subscriptionKey)
    {
        using (var client = new HttpClient())
        {
            client.DefaultRequestHeaders.Add("Ocp-Apim-Subscription-Key", subscriptionKey);
            UriBuilder uriBuilder = new UriBuilder(fetchUri);

            var result = await client.PostAsync(uriBuilder.Uri.AbsoluteUri, null);
            Console.WriteLine("Token Uri: {0}", uriBuilder.Uri.AbsoluteUri);
            return await result.Content.ReadAsStringAsync();
        }
    }
}

Python sample

# Request module must be installed.
# Run pip install requests if necessary.
import requests

subscription_key = 'REPLACE_WITH_YOUR_KEY'


def get_token(subscription_key):
    fetch_token_url = 'https://westus.api.cognitive.microsoft.com/sts/v1.0/issueToken'
    headers = {
        'Ocp-Apim-Subscription-Key': subscription_key
    }
    response = requests.post(fetch_token_url, headers=headers)
    access_token = str(response.text)
    print(access_token)

How to use an access token

The access token should be sent to the service as the Authorization: Bearer <TOKEN> header. Each access token is valid for 10 minutes. You can get a new token at any time, but to minimize network traffic and latency, we recommend using the same token for nine minutes.

Here's a sample HTTP request to the speech-to-text REST API for short audio:

POST /cognitiveservices/v1 HTTP/1.1
Authorization: Bearer YOUR_ACCESS_TOKEN
Host: westus.stt.speech.microsoft.com
Content-type: application/ssml+xml
Content-Length: 199
Connection: Keep-Alive

// Message body here...

Get a list of voices

You can use the voices/list endpoint to get a full list of voices for a specific region or endpoint:

Region Endpoint
Australia East https://australiaeast.tts.speech.microsoft.com/cognitiveservices/voices/list
Brazil South https://brazilsouth.tts.speech.microsoft.com/cognitiveservices/voices/list
Canada Central https://canadacentral.tts.speech.microsoft.com/cognitiveservices/voices/list
Central US https://centralus.tts.speech.microsoft.com/cognitiveservices/voices/list
China East 2 https://chinaeast2.tts.speech.azure.cn/cognitiveservices/voices/list
China North 2 https://chinanorth2.tts.speech.azure.cn/cognitiveservices/voices/list
East Asia https://eastasia.tts.speech.microsoft.com/cognitiveservices/voices/list
East US https://eastus.tts.speech.microsoft.com/cognitiveservices/voices/list
East US 2 https://eastus2.tts.speech.microsoft.com/cognitiveservices/voices/list
France Central https://francecentral.tts.speech.microsoft.com/cognitiveservices/voices/list
Germany West Central https://germanywestcentral.tts.speech.microsoft.com/cognitiveservices/voices/list
India Central https://centralindia.tts.speech.microsoft.com/cognitiveservices/voices/list
Japan East https://japaneast.tts.speech.microsoft.com/cognitiveservices/voices/list
Japan West https://japanwest.tts.speech.microsoft.com/cognitiveservices/voices/list
Jio India West https://jioindiawest.tts.speech.microsoft.com/cognitiveservices/voices/list
Korea Central https://koreacentral.tts.speech.microsoft.com/cognitiveservices/voices/list
North Central US https://northcentralus.tts.speech.microsoft.com/cognitiveservices/voices/list
North Europe https://northeurope.tts.speech.microsoft.com/cognitiveservices/voices/list
Norway East https://norwayeast.tts.speech.microsoft.com/cognitiveservices/voices/list
South Central US https://southcentralus.tts.speech.microsoft.com/cognitiveservices/voices/list
Southeast Asia https://southeastasia.tts.speech.microsoft.com/cognitiveservices/voices/list
Switzerland North https://switzerlandnorth.tts.speech.microsoft.com/cognitiveservices/voices/list
Switzerland West https://switzerlandwest.tts.speech.microsoft.com/cognitiveservices/voices/list
US Gov Arizona https://usgovarizona.tts.speech.azure.us/cognitiveservices/voices/list
US Gov Virginia https://usgovvirginia.tts.speech.azure.us/cognitiveservices/voices/list
UK South https://uksouth.tts.speech.microsoft.com/cognitiveservices/voices/list
West Central US https://westcentralus.tts.speech.microsoft.com/cognitiveservices/voices/list
West Europe https://westeurope.tts.speech.microsoft.com/cognitiveservices/voices/list
West US https://westus.tts.speech.microsoft.com/cognitiveservices/voices/list
West US 2 https://westus2.tts.speech.microsoft.com/cognitiveservices/voices/list
West US 3 https://westus3.tts.speech.microsoft.com/cognitiveservices/voices/list

Tip

Voices in preview are available in only these three regions: East US, West Europe, and Southeast Asia.

Request headers

This table lists required and optional headers for text-to-speech requests:

Header Description Required or optional
Ocp-Apim-Subscription-Key Your subscription key for the Speech service. Either this header or Authorization is required.
Authorization An authorization token preceded by the word Bearer. For more information, see Authentication. Either this header or Ocp-Apim-Subscription-Key is required.

Request body

A body isn't required for GET requests to this endpoint.

Sample request

This request requires only an authorization header:

GET /cognitiveservices/voices/list HTTP/1.1

Host: westus.tts.speech.microsoft.com
Ocp-Apim-Subscription-Key: YOUR_SUBSCRIPTION_KEY

Sample response

This response has been truncated to illustrate the structure of a response.

Note

Voice availability varies by region or endpoint.

[

    {
    "Name": "Microsoft Server Speech Text to Speech Voice (en-US, JennyNeural)",
    "DisplayName": "Jenny",
    "LocalName": "Jenny",
    "ShortName": "en-US-JennyNeural",
    "Gender": "Female",
    "Locale": "en-US",
    "StyleList": [
      "chat",
      "customerservice",
      "newscast-casual",
      "assistant",
    ],
    "SampleRateHertz": "24000",
    "VoiceType": "Neural",
    "Status": "GA"
  },

    ...

     {
    "Name": "Microsoft Server Speech Text to Speech Voice (en-US, JennyMultilingualNeural)",
    "ShortName": "en-US-JennyMultilingualNeural",
    "DisplayName": "Jenny Multilingual",
    "LocalName": "Jenny Multilingual",
    "Gender": "Female",
    "Locale": "en-US",
    "SampleRateHertz": "24000",
    "VoiceType": "Neural",
    "SecondaryLocaleList": [
        "de-DE",
        "en-AU",
        "en-CA",
        "en-GB",
        "es-ES",
        "es-MX",
        "fr-CA",
        "fr-FR",
        "it-IT",
        "ja-JP",
        "ko-KR",
        "pt-BR",
        "zh-CN"
      ],
    "Status": "Preview"
    },
    
  ...
    
    {
    "Name": "Microsoft Server Speech Text to Speech Voice (ga-IE, OrlaNeural)",
    "DisplayName": "Orla",
    "LocalName": "Orla",
    "ShortName": "ga-IE-OrlaNeural",
    "Gender": "Female",
    "Locale": "ga-IE",
    "SampleRateHertz": "24000",
    "VoiceType": "Neural",
    "Status": "GA"
  },

  ...

   {
    "Name": "Microsoft Server Speech Text to Speech Voice (zh-CN, YunxiNeural)",
    "DisplayName": "Yunxi",
    "LocalName": "云希",
    "ShortName": "zh-CN-YunxiNeural",
    "Gender": "Male",
    "Locale": "zh-CN",
    "StyleList": [
      "Calm",
      "Fearful",
      "Cheerful",
      "Disgruntled",
      "Serious",
      "Angry",
      "Sad",
      "Depressed",
      "Embarrassed"
    ],
    "SampleRateHertz": "24000",
    "VoiceType": "Neural",
    "Status": "GA"
  },

    ...

]

HTTP status codes

The HTTP status code for each response indicates success or common errors.

HTTP status code Description Possible reason
200 OK The request was successful.
400 Bad request A required parameter is missing, empty, or null. Or, the value passed to either a required or optional parameter is invalid. A common reason is a header that's too long.
401 Unauthorized The request is not authorized. Make sure your subscription key or token is valid and in the correct region.
429 Too many requests You have exceeded the quota or rate of requests allowed for your subscription.
502 Bad gateway There's a network or server-side problem. This status might also indicate invalid headers.

Convert text to speech

The v1 endpoint allows you to convert text to speech by using Speech Synthesis Markup Language (SSML).

Regions and endpoints

These regions are supported for text-to-speech through the REST API. Be sure to select the endpoint that matches your subscription region.

Prebuilt neural voices

Use this table to determine availability of neural voices by region or endpoint:

Region Endpoint
Australia East https://australiaeast.tts.speech.microsoft.com/cognitiveservices/v1
Brazil South https://brazilsouth.tts.speech.microsoft.com/cognitiveservices/v1
Canada Central https://canadacentral.tts.speech.microsoft.com/cognitiveservices/v1
Central US https://centralus.tts.speech.microsoft.com/cognitiveservices/v1
China East 2 https://chinaeast2.tts.speech.azure.cn/cognitiveservices/v1
China North 2 https://chinanorth2.tts.speech.azure.cn/cognitiveservices/v1
East Asia https://eastasia.tts.speech.microsoft.com/cognitiveservices/v1
East US https://eastus.tts.speech.microsoft.com/cognitiveservices/v1
East US 2 https://eastus2.tts.speech.microsoft.com/cognitiveservices/v1
France Central https://francecentral.tts.speech.microsoft.com/cognitiveservices/v1
Germany West Central https://germanywestcentral.tts.speech.microsoft.com/cognitiveservices/v1
India Central https://centralindia.tts.speech.microsoft.com/cognitiveservices/v1
Japan East https://japaneast.tts.speech.microsoft.com/cognitiveservices/v1
Japan West https://japanwest.tts.speech.microsoft.com/cognitiveservices/v1
Jio India West https://jioindiawest.tts.speech.microsoft.com/cognitiveservices/v1
Korea Central https://koreacentral.tts.speech.microsoft.com/cognitiveservices/v1
North Central US https://northcentralus.tts.speech.microsoft.com/cognitiveservices/v1
North Europe https://northeurope.tts.speech.microsoft.com/cognitiveservices/v1
Norway East https://norwayeast.tts.speech.microsoft.com/cognitiveservices/v1
South Central US https://southcentralus.tts.speech.microsoft.com/cognitiveservices/v1
Southeast Asia https://southeastasia.tts.speech.microsoft.com/cognitiveservices/v1
Sweden Central https://swedencentral.tts.speech.microsoft.com/cognitiveservices/v1
Switzerland North https://switzerlandnorth.tts.speech.microsoft.com/cognitiveservices/v1
Switzerland West https://switzerlandwest.tts.speech.microsoft.com/cognitiveservices/v1
UAE North https://uaenorth.tts.speech.microsoft.com/cognitiveservices/v1
US Gov Arizona https://usgovarizona.tts.speech.azure.us/cognitiveservices/v1
US Gov Virginia https://usgovvirginia.tts.speech.azure.us/cognitiveservices/v1
UK South https://uksouth.tts.speech.microsoft.com/cognitiveservices/v1
West Central US https://westcentralus.tts.speech.microsoft.com/cognitiveservices/v1
West Europe https://westeurope.tts.speech.microsoft.com/cognitiveservices/v1
West US https://westus.tts.speech.microsoft.com/cognitiveservices/v1
West US 2 https://westus2.tts.speech.microsoft.com/cognitiveservices/v1
West US 3 https://westus3.tts.speech.microsoft.com/cognitiveservices/v1

Tip

Voices in preview are available in only these three regions: East US, West Europe, and Southeast Asia.

Custom neural voices

If you've created a custom neural voice font, use the endpoint that you've created. You can also use the following endpoints. Replace {deploymentId} with the deployment ID for your neural voice model.

Region Training Deployment Endpoint
Australia East Yes Yes https://australiaeast.voice.speech.microsoft.com/cognitiveservices/v1?deploymentId={deploymentId}
Brazil South No Yes https://brazilsouth.voice.speech.microsoft.com/cognitiveservices/v1?deploymentId={deploymentId}
Canada Central No Yes https://canadacentral.voice.speech.microsoft.com/cognitiveservices/v1?deploymentId={deploymentId}
Central US No Yes https://centralus.voice.speech.microsoft.com/cognitiveservices/v1?deploymentId={deploymentId}
East Asia No Yes https://eastasia.voice.speech.microsoft.com/cognitiveservices/v1?deploymentId={deploymentId}
East US Yes Yes https://eastus.voice.speech.microsoft.com/cognitiveservices/v1?deploymentId={deploymentId}
East US 2 Yes Yes https://eastus2.voice.speech.microsoft.com/cognitiveservices/v1?deploymentId={deploymentId}
France Central No Yes https://francecentral.voice.speech.microsoft.com/cognitiveservices/v1?deploymentId={deploymentId}
Germany West Central No Yes https://germanywestcentral.voice.speech.microsoft.com/cognitiveservices/v1?deploymentId={deploymentId}
India Central Yes Yes https://centralindia.voice.speech.microsoft.com/cognitiveservices/v1?deploymentId={deploymentId}
Japan East Yes Yes https://japaneast.voice.speech.microsoft.com/cognitiveservices/v1?deploymentId={deploymentId}
Japan West No Yes https://japanwest.voice.speech.microsoft.com/cognitiveservices/v1?deploymentId={deploymentId}
Jio India West No Yes https://jioindiawest.voice.speech.microsoft.com/cognitiveservices/v1?deploymentId={deploymentId}
Korea Central Yes Yes https://koreacentral.voice.speech.microsoft.com/cognitiveservices/v1?deploymentId={deploymentId}
North Central US No Yes https://northcentralus.voice.speech.microsoft.com/cognitiveservices/v1?deploymentId={deploymentId}
North Europe Yes Yes https://northeurope.voice.speech.microsoft.com/cognitiveservices/v1?deploymentId={deploymentId}
Norway East No Yes https://norwayeast.voice.speech.microsoft.com/cognitiveservices/v1?deploymentId={deploymentId}
South Africa North No Yes https://southafricanorth.voice.speech.microsoft.com/cognitiveservices/v1?deploymentId={deploymentId}
South Central US Yes Yes https://southcentralus.voice.speech.microsoft.com/cognitiveservices/v1?deploymentId={deploymentId}
Southeast Asia Yes Yes https://southeastasia.voice.speech.microsoft.com/cognitiveservices/v1?deploymentId={deploymentId}
Switzerland North No Yes https://switzerlandnorth.voice.speech.microsoft.com/cognitiveservices/v1?deploymentId={deploymentId}
Switzerland West No Yes https://switzerlandwest.voice.speech.microsoft.com/cognitiveservices/v1?deploymentId={deploymentId}
UAE North No Yes https://uaenorth.voice.speech.microsoft.com/cognitiveservices/v1?deploymentId={deploymentId}
UK South Yes Yes https://uksouth.voice.speech.microsoft.com/cognitiveservices/v1?deploymentId={deploymentId}
West Central US No Yes https://westcentralus.voice.speech.microsoft.com/cognitiveservices/v1?deploymentId={deploymentId}
West Europe Yes Yes https://westeurope.voice.speech.microsoft.com/cognitiveservices/v1?deploymentId={deploymentId}
West US Yes Yes https://westus.voice.speech.microsoft.com/cognitiveservices/v1?deploymentId={deploymentId}
West US 2 Yes Yes https://westus2.voice.speech.microsoft.com/cognitiveservices/v1?deploymentId={deploymentId}
West US 3 No Yes https://westus3.voice.speech.microsoft.com/cognitiveservices/v1?deploymentId={deploymentId}

Note

The preceding regions are available for neural voice model hosting and real-time synthesis. Custom neural voice training is only available in some regions. But users can easily copy a neural voice model from these regions to other regions in the preceding list.

Long Audio API

The Long Audio API is available in multiple regions with unique endpoints:

Region Endpoint
Australia East https://australiaeast.customvoice.api.speech.microsoft.com
East US https://eastus.customvoice.api.speech.microsoft.com
India Central https://centralindia.customvoice.api.speech.microsoft.com
South Central US https://southcentralus.customvoice.api.speech.microsoft.com
Southeast Asia https://southeastasia.customvoice.api.speech.microsoft.com
UK South https://uksouth.customvoice.api.speech.microsoft.com
West Europe https://westeurope.customvoice.api.speech.microsoft.com

Request headers

This table lists required and optional headers for text-to-speech requests:

Header Description Required or optional
Authorization An authorization token preceded by the word Bearer. For more information, see Authentication. Required
Content-Type Specifies the content type for the provided text. Accepted value: application/ssml+xml. Required
X-Microsoft-OutputFormat Specifies the audio output format. For a complete list of accepted values, see Audio outputs. Required
User-Agent The application name. The provided value must be fewer than 255 characters. Required

Request body

If you're using a custom neural voice, the body of a request can be sent as plain text (ASCII or UTF-8). Otherwise, the body of each POST request is sent as SSML. SSML allows you to choose the voice and language of the synthesized speech that the text-to-speech feature returns. For a complete list of supported voices, see Language and voice support for the Speech service.

Sample request

This HTTP request uses SSML to specify the voice and language. If the body length is long, and the resulting audio exceeds 10 minutes, it's truncated to 10 minutes. In other words, the audio length can't exceed 10 minutes.

POST /cognitiveservices/v1 HTTP/1.1

X-Microsoft-OutputFormat: riff-24khz-16bit-mono-pcm
Content-Type: application/ssml+xml
Host: westus.tts.speech.microsoft.com
Content-Length: <Length>
Authorization: Bearer [Base64 access_token]
User-Agent: <Your application name>

<speak version='1.0' xml:lang='en-US'><voice xml:lang='en-US' xml:gender='Male'
    name='en-US-ChristopherNeural'>
        Microsoft Speech Service Text-to-Speech API
</voice></speak>

* For the Content-Length, you should use your own content length. In most cases, this value is calculated automatically.

HTTP status codes

The HTTP status code for each response indicates success or common errors:

HTTP status code Description Possible reason
200 OK The request was successful. The response body is an audio file.
400 Bad request A required parameter is missing, empty, or null. Or, the value passed to either a required or optional parameter is invalid. A common reason is a header that's too long.
401 Unauthorized The request is not authorized. Make sure your subscription key or token is valid and in the correct region.
415 Unsupported media type It's possible that the wrong Content-Type value was provided. Content-Type should be set to application/ssml+xml.
429 Too many requests You have exceeded the quota or rate of requests allowed for your subscription.
502 Bad gateway There's a network or server-side problem. This status might also indicate invalid headers.

If the HTTP status is 200 OK, the body of the response contains an audio file in the requested format. This file can be played as it's transferred, saved to a buffer, or saved to a file.

Audio outputs

This is a list of supported audio formats that are sent in each request as the X-Microsoft-OutputFormat header. Each format incorporates a bit rate and encoding type. The Speech service supports 48-kHz, 24-kHz, 16-kHz, and 8-kHz audio outputs. Prebuilt neural voices are created from samples that use a 24-khz sample rate. All voices can upsample or downsample to other sample rates when synthesizing.

Streaming Non-Streaming
audio-16khz-16bit-32kbps-mono-opus riff-8khz-8bit-mono-alaw
audio-16khz-32kbitrate-mono-mp3 riff-8khz-8bit-mono-mulaw
audio-16khz-64kbitrate-mono-mp3 riff-8khz-16bit-mono-pcm
audio-16khz-128kbitrate-mono-mp3 riff-24khz-16bit-mono-pcm
audio-24khz-16bit-24kbps-mono-opus riff-48khz-16bit-mono-pcm
audio-24khz-16bit-48kbps-mono-opus
audio-24khz-48kbitrate-mono-mp3
audio-24khz-96kbitrate-mono-mp3
audio-24khz-160kbitrate-mono-mp3
audio-48khz-96kbitrate-mono-mp3
audio-48khz-192kbitrate-mono-mp3
ogg-16khz-16bit-mono-opus
ogg-24khz-16bit-mono-opus
ogg-48khz-16bit-mono-opus
raw-8khz-8bit-mono-alaw
raw-8khz-8bit-mono-mulaw
raw-8khz-16bit-mono-pcm
raw-16khz-16bit-mono-pcm
raw-16khz-16bit-mono-truesilk
raw-24khz-16bit-mono-pcm
raw-24khz-16bit-mono-truesilk
raw-48khz-16bit-mono-pcm
webm-16khz-16bit-mono-opus
webm-24khz-16bit-24kbps-mono-opus
webm-24khz-16bit-mono-opus

Note

en-US-AriaNeural, en-US-JennyNeural and zh-CN-XiaoxiaoNeural are available in public preview in 48Khz output. Other voices support 24khz upsampled to 48khz output.

Note

If your selected voice and output format have different bit rates, the audio is resampled as necessary. You can decode the ogg-24khz-16bit-mono-opus format by using the Opus codec.

Next steps